Install a simple Martin Thinline 332 in each of your acoustic guitars and then get yourself a Fishman GII preamp, which clips onto your belt. That's what I do. The sound is awesome and it's easy on the pocket book. Fishman makes both products and they were meant to be used together. By itself, the Thinline is thin and tinny.

I just got my 332 thineline. I installed it in my son's guiter. All of the strings have equal volume and the tone is great.

I bought one of these Martin Thinline 332 pickups for self installation. The sound results were poor - The two highest (B/E) and lowest (E) strings had much weaker volume than the middle three. The middle two (D/G) were very hot. Because this was the first pick-up install I had performed, I thought maybe I mishandled the pick-up strip, causing the volume issue. So, I ordered a second one. I was meticulous with this install, and same exact volume difference problem. The only way you could play out somewhere professionally with this would be to adjust your attack on the strings with a weaker signal. Too much to think about. If you want even volume across the strings, don't purchase this product.

I just had the 332 professionally installed in my D28 by an authorized Martin repair center. I was a bit nervous about having the guitar modifed in any way. The sound just blew me away. It doesn't sound like a piezo pickup. Without a preamp it is still very loud when plugged into my Genz Benz Shenandoah 85. Since I needed a volume control, I inserted an old DOD FET preamp between the guitar an the amp. WOW!!! This really brought the sound to where it is pure Martin. I hav an Alvarez and it is goung to get the same treatment.

I love this unit. It does what it does and sounds great. As with any new piece of equipment you will need to tweak your settings on your pa or eq to even out the tone(big deal)!